Lubricant



Patented Oct. 12, 1948 Arnold J. Morway,

Clark Township,

Union County, and John C. Zimmer, Union, N. J assignors to Standard OilDevelopment Company, a corporation of Delaware No Drawing. ApplicationDecember 27, 1941, Serial No. 424,590

Claims.

The present invention is concerned with the production of improvedlubricating grease compositions. The invention more particularly relatesto a grease composition which is especially adapted for use underextreme variations in climatic conditions, such as wide variations intemperature and humidity. The preferred composition comprises a mineraloil base thickened to a grease consistency with a mixture'of saturatedfatty acid soaps of lithium and aluminum It is known in the art toprepare various lu bricating grease compositions adapted for partic ularuses. The uses in which grease compositions are employed present a widevariety of conditions and generally a grease prepared with a given setof conditions in mind is not suitable for use under a difierent set ofconditions. Airplanes are controlled in flight by special mechanismssuch as rudders, elevators, and ailerons which are attached to the mainportions of the airplane such as fuselage and wings by speciallydesigned hinges. These hinges have metal to metal contact'bearingsurfaces which offer a very difficult lubrication problem. Airplanes areoperated under the most severe changes in climatic conditions and sincethe failure of even one part of the mechanism might well result in acatastrophe, it is imperative that all parts of the plane be maintainedin as perfect a mechanical condition as possible. In order to be in goodmechanical condition all movable parts should be free and welllubricated at all times. It is not uncommon for a plane during a singletrip to be subjected to extremely high ground temperatures, subzerotemperatures in the upperatmosphere as well as conditions of highhumidity such as rain, snow, or ice.v Any lubricant used upon thecontrol mechanisms of the plane must be capable of withstanding theseconditions without disintegration.

High temperature greases such as the sodium soap greases are known tothe art, however they are quite water-soluble and readily disintegrateunder humid conditions. Water insoluble greases, such as the calciumsoap greases, are also known, but these compositions will not withstandhigh temperatures. Aluminum soap greases are also water insoluble buthave a relatively low transient point where they become fluid or rubberyand run or pull out of the bearing.

It is an object of this invention to produce a grease composition whichwill provide adequate lubrication at both high and low temperatures andwill not decompose in the presence of excessive moisture. This and otherobjects will be apparent to those skilled in the art upon reading thefollowing description.

The grease composition made in accordance with the present inventioncomprises essentially a low pour point lubricating mineral oildistillate, a lithium soap of a saturated fatty acid and an aluminumsoap of a saturated fatty acid, although it is preferred to use from 10to 20% of the lithium soap and from 0.25 to 2% of the aluminum soapbased upon the total composition. A small amount of an anti-oxidant, say0.2%, such as phenyl alpha naphthylamine, may be used if desired. 7

Although any of the numerous types of low pour point lubricating oilsmay be used as the base for compositions made in accordance with thisinvention, it is preferred to use a Coastal type oil having a viscosity,in the range of from about 58 seconds to seconds S. U. V. at 100 F. anda cold test below 40 F.

For the formation of the soap utilized in the production of the greases,any saturated fats or saturated fatty acids derived therefrom, such asstearin or stearic'acid may be used, although it is preferred to use thesaturated acids derived from hydrogenated fish 011.

Any of the methods customarily employed in the compounding of greasesmay be used in the production of the compositions of this invention. Thesoaps may be produced separately and then mixed with the oil by heat andagitation; or preferably the saturated fat or fatty acid to be combinedwith the lithium may be dissolved in a portion of the lubricating oil byheating the oil sufficiently to dissolve the fat or acid in the oil,reacting thefat or fatty acid with lithium hydroxide and then theremainder of the lubricating oil having the aluminum soap dispersedtherein may be added after which the mixture is brought to a clearsolution and the water driven off by heating and stirring, theanti-oxidant added and the mixture permitted to cool. It is preferred tomake the aluminum soap separately and then dissolve it in a portion ofthe lubricating oil although the aluminum soap can be produced from thesaturated fatty acid and aluminum hydroxide in situ EXAMPLE 1 PercentHydrogenated fish oil acids 13.00 Lithiumhydroxide (monohydrate) 2.00Aluminum stearate 1 -i 0.50

Lubricating oil (low viscosity, low pour oil) 42.125 Lubricating oil(low pour Coastal oil) 42.125 Phenyl alpha naphthylamine 0.2

In compounding the above formula the acid and approximately one-fourthof. the oil are charged into a fire-heated kettle equipped withagitators. The mixture is then heated and stirred to a temperature ofabout 150 F, or until all the acid is melted and dissolved in the oiland then the lithium hydroxide dissolved in boiling water'is added tothe acid-oil solution. Heating andagitation is continued and thetemperature permitted to slowly rise until'all of the water is boiledofi. During this continued heating small additional amounts of the oilare intermittently added. The aluminum soap is then dissolved inapproximately one-fourth of the lubricating oil and this solutiontogether with the remainder of the lubricating oilis-added to the kettleafter the water has been boiled. off. The temperature of the kettle isthen raised to within 'therange of from-350 to 400 F. or preferablyabout-370 R, at which temperature the grease is completely melted. Thephenyl alpha .naphthylamine-is then added. after which agitation andheating is discontinued and the grease permitted to coolforming a smoothalmost transparent block. The grease is then worked to a smooth paste inthe kettle, filtered and packaged. The grease thus produced has thefollowing characteristics:

A.S."T. M.worked penetration at77" F. 23'0 Melting point F. 374 Freeacidity per 'cent 1 0.21

1 Calculated as oleic acid.

Low temperature testat 60 F.

:Test and-apparatus :described in paper presented .before the-44thannual meeting of the American Society for Testing Materials held :inChicago, Illinois, 6/23-27 /41, Performance Specifications for Greases,Robert C. Adams and Harrison Patten.

Force to Approximate Time for 1 Turn 3 Bear- Torque Revolution ingsGins. Gms.-Cm. Secs.

EXAMPLEZ 100 parts of hydrogenated fish oil acids are neutralized with15.73 parts of a lithium hydroxide (monohydrate) dissolved in Water. Theresulting lithium soap is dried and powdered.

Percent Lithium soap (described above) 15.00 Aluminum stearate 0.60Phenyl alpha naphthylamine 0.50 Lubricating oil (low pour,Coastal oil-40'F. pour point, 588. S. U. viscosity at 100 F.) 83.90

"The lithium soap and aluminum stearate are added to a fire-heatedkettle, and one-fourth of the oil added. These ingredients are Worked toa smooth paste and the temperature raised to 300 F. The balance of theoil is added and the kettle covered and the temperature raised to 400 F.Stirring and heating is discontinued and the material cooled to roomtemperature. When cool the solid mass is worked to a smooth plastichomogeneous grease.

The physical properties of this product closely resemble those for thegrease described inExample. 1.

What is claimed is:

1. Anlimproved lubricating grease composition comprising a majorproportion of a low pour point lubricating mineral oil distillate,aminor proportion, sufiicient to thicken said oil to a greaseconsistencymf a lithium soap of a saturated fatty acid and an aluminumsoap of a saturated fatty acid, said aluminum soap being present in anamount substantially smaller than that of said lithium soap but not lessthan 0.25% of the total composition.

.2. A composition as defined by claim 1, in which the lithium soap or asaturated fatty acid isthe lithium soap of hydrogenated 'fish oil acids.

.3.. Acomposition as definedby claim 1 in which the aluminumsoap isaluminum stearate.

4.. An improved lubricating grease composition comprising :a majorproportion of a low pour point lubricating mineral oil distillate, aminor proportion ofa lithium soap of a saturatedfatty acid amounting toabout'lO to 20% of thetotal compositionand a minor proportion of analuminumsoa-pofa saturated fatty acid amounting to about 0.25 to 1% oftheatotal composition.

5. A composition as defined by claim 1 in which said. low pour pointmineral oil distillate is a low viscosity distillate,

ARNOLD J. MORWAY. JOHN 'C. ZIMMER.

REFERENCES 'CITED The following references are of record in the file.ofthis patent:

UNITED STATES PATENTS Number Name Date 1,989,196 I-Iil-liker Jane 29,1935 2,024,990 Kaufman Dec.-17,.-1935 2,066,958 Brownback Jan. 5, 19372,186,514 Yagle Jan. 9,-1940 2,197,433 Lutz Apr. 16, 1940 2,274,673Earle Mar. 3, 1942 2,293;052 Earle Aug. 18, 1942

